LTIRoles

This is a small gem that maps the LTI standard roles into a ruby symbol. I created this for use with cancancan.

Add this line to your application's Gemfile:

gem 'lti_roles'

And then execute:

$ bundle

Or install it yourself as:

$ gem install lti_roles

LTIRoles has a RoleManager class that simply you initialize by passing your launch params roles string. RoleManager expects your roles to include the full URN. See this page for a list of possible roles.

Example:

  roles = LTIRoles::RoleManager.new('urn:lti:instrole:ims/lis/Instructor,urn:lti:instrole:ims/lis/Student,urn:lti:role:ims/lis/Instructor,urn:lti:sysrole:ims/lis/User')

  roles.institution_roles
  => ['instructor', 'student']

  roles.context_roles
  => ['instructor']

Inside your launch controller you might save off the launch roles.

  current_user.roles = LTIRoles::RoleManager.new('urn:lti:instrole:ims/lis/Instructor,urn:lti:instrole:ims/lis/Student,urn:lti:role:ims/lis/Instructor,urn:lti:sysrole:ims/lis/User')

Then you can check abilities like so.

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new # guest user (not logged in)
    user.roles ||= LTIRoles::RoleManager.new

    if user.roles.institution_roles.include?(:administrator)
      can :manage, :all
    end

    if user.roles.institution_roles.include?(:instructor)
      can :read, :all
    end
  end
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/CerebralStorm/lti_roles.

The gem is available as open source under the terms of the MIT License.